1. Field of the Invention
The present invention relates to a high-hardness cold-deformed austenitic stainless steel exhibiting a superior non-magnetic property.
2. Description of the prior art
Parts used in electronic equipment which utilize electro-magnetism are required to be non-magnetic. In particular, various kinds of components such as VTR cylinders and capstans, and VTR cassette tape guide rollers and guide pins are required to not only have a non-magnetic property but further, high hardness from the view point of wear resistance is desirable. These parts are also required to have high corrosion resistance and from these points, of view, an austenitic stainless steel is mostly used. In general, austenitic stainless steels, such as Type 305 and Type 316, which have a stable austenitic structure at room temperature are used conventionally.
Although high-hardness austenitic stainless steels in which Manganese is partially substituted for Nickel are disclosed in Japanese Unexamined Patent Publications Nos. 84324/1986 and 213351/1986, the former steel being inferior in hot workability (the term is defined as the workability for the production of steel sheet, strip or wire, etc. by hot-working) and the latter steel being expensive, there has been a strong demand for improvement in this regard. Japanese Unexamined Patent Publication No. 37953/1986 discloses a process for producing a non-magnetic steel, but this publication is silent regarding high hardness and hot workability.
To overcome the problem of inferior hot workability in high-hardness austenitic stainless steels, the present inventors studied the Mn-Ni-Cr austenitic stainless steels. As a result, a stainless steel was developed which exhibits good hot workability, high corrosion resistance, high hardness and is non-magnetic after cold forming. This stainless steel is very useful for parts of electronic equipment and is especially suitable for use in various kinds of shafts for VTRs and VTR cassette tapes.